Storing sea level observations

The data logger measures water height periodically. A data item may be an average of a continuous series of measurements made during a period set by the operator, called the integration time.

Data processing

To digitally track the high-frequency signals concerning residual swell and chop, the measurements may be integrated over a time period of 2 minutes (integration time), with a measurement rate of 10 minutes (archiving period).

The average value is archived on a date corresponding to the middle of the integration period.

Data correction

The data logger can also correct measurements based on the results of sensor calibration (water depth reduced to chart datum).

Data transmission

The data stored in the data logger can be regularly transmitted via:

the wired telephone network (ADSL);

the mobile telephone network (GPRS);

the radio system (VHF);

satellites transmitter (weather satellites).

When using satellite communications, the measurement transmission rate is set according to the conditions of the agency in charge of the satellite.

For tidal observations used in the context of a warning system (tsunamis, storm surges) two separate data transmission methods should be used to create a fail-safe system.